Sweat gland
tumors have been classified according to their presumed physiological counterpart of the sweat apparatus. Both benign
poroma and malignant porocarcinoma are thought to be acrosyringeal
tumors. In order to specify this general assumption, we performed histochemistry and immunohistochemistry on
paraffin sections of 29
poromas and eight porocarcinomas. In detail, we used Lapham's
stain, Masson's
silver impregnation, and immunoperoxidase staining with glandular marker
antibodies against
glycoproteins (CEA, LS59, NKI/C-3) and
intermediate filament proteins (wide spectrum
keratin, Cam 5.2, Vim 9(1)).
Poromas disclosed some scattered S100-positive dendritic cells, red-stained cells in Lapham's method, several
silver impregnated dendritic cells, and numerous cells surrounding
poromas which were positive for LS59 and NKI/C-3. The labeling with wide spectrum
keratin antiserum was low compared to epidermal keratinocytes. Porocarcinomas made some difference. CEA-positive single vacuolated cells could be observed, and S100-positive cells failed to show dendrites as in
poromas. Some
tumor cell clusters were stained weakly with LS59 and NKI/C-3 in addition to surrounding cells in both
tumor entities. Three out of eight porocarcinomas disclosed sparsely distributed scattered cells weakly reactive with
antibodies Cam 5.2 or Vim 9(1). In general, malignant porocarcinomas expressed a greater variety of cellular markers than benign
poromas. The differentiation of both
tumors, however, was directed toward inner duct cells and myoepithelium. Since myoepithelial cells are missing in normal acrosyringium,
poromas and porocarcinomas are thought to be sweat gland
tumors related to the distal portion of the dermal duct.